Refactor I2C device scanning and update display pin assignments

- Changed I2C scanning function to probe only expected device addresses, improving startup reliability.
- Updated logging to provide clearer output for found and missing devices.
- Modified I2C SDA and SCL pin assignments from 6 and 7 to 8 and 9, respectively, to accommodate hardware changes.
- Added a timeout for I2C communication to enhance robustness.

platformio.ini

@@ -16,11 +16,12 @@ lib_deps =
 board_upload.flash_size = 16MB
 board_build.partitions = default_16MB.csv
 board_build.arduino.memory_type = qio_opi
-board_build.extra_flags = -DBOARD_HAS_PSRAM
 
 ; board_build.filesystem = spiffs
 
 build_flags =
+  -D BOARD_HAS_PSRAM
+  -D ARDUINO_USB_CDC_ON_BOOT=1
   -D PB_VERSION=\"1.0.0\"
   -D PB_HOSTNAME=\"faceplant\"
   -D PB_TZ=\"America/New_York\"

src/ui/Display.cpp

@@ -1,19 +1,27 @@
 #include "Display.h"
 
-static void logI2CScan() {
-  Serial.println("[Display] Scanning I2C bus...");
+static void logExpectedI2CDevices() {
+  // Probe only expected addresses to reduce startup risk if the bus is unhealthy.
+  const uint8_t addrs[] = {0x3C, 0x3D, 0x10, 0x36, 0x68}; // SH1106, VEML7700, MAX17048, MPU6050
+  Serial.println("[Display] Probing expected I2C addresses...");
   uint8_t found = 0;
-  for (uint8_t addr = 1; addr < 127; addr++) {
+  for (uint8_t i = 0; i < sizeof(addrs); i++) {
+    uint8_t addr = addrs[i];
     Wire.beginTransmission(addr);
     uint8_t err = Wire.endTransmission();
+    Serial.print("[Display] 0x");
+    if (addr < 16) Serial.print('0');
+    Serial.print(addr, HEX);
+    Serial.print(" -> ");
     if (err == 0) {
-      Serial.print("[Display] I2C device @ 0x");
-      if (addr < 16) Serial.print('0');
-      Serial.println(addr, HEX);
+      Serial.println("OK");
       found++;
+    } else {
+      Serial.print("ERR ");
+      Serial.println(err);
     }
   }
-  if (found == 0) Serial.println("[Display] No I2C devices found");
+  if (found == 0) Serial.println("[Display] No expected I2C devices responded");
 }
 
 void Display::begin() {
@@ -27,8 +35,9 @@ void Display::begin() {
   Serial.println(OLED_ADDR, HEX);
 
   Wire.begin(PIN_SDA, PIN_SCL);
+  Wire.setTimeOut(20);
   delay(20);
-  logI2CScan();
+  logExpectedI2CDevices();
 
   Serial.println("[Display] Initializing SH1106...");
   _ok = _oled.begin(OLED_ADDR, true);

src/ui/Display.h

@@ -18,8 +18,8 @@ public:
   bool displayEnabled() const { return _displayEnabled; }
 
 private:
-  static constexpr int PIN_SDA = 6;
-  static constexpr int PIN_SCL = 7;
+  static constexpr int PIN_SDA = 8;
+  static constexpr int PIN_SCL = 9;
   static constexpr uint8_t OLED_ADDR = 0x3C; // try 0x3D if blank
   Adafruit_SH1106G _oled = Adafruit_SH1106G(128, 64, &Wire, -1);
   bool _ok = false;